Current computers have high power consumption even when idle. It is beneficial to reduce the power consumption of computing devices for environmental reasons and to reduce operating cost. Additionally, for battery powered devices, reduced power consumption enables increased battery life or alternatively the size, weight and cost of the battery can be reduced.
A number of solutions have been proposed to reduce the power consumption of battery powered computing devices, such as laptop computers and handheld devices. These include mechanisms which shut down or suspend the device, and/or which switch off associated devices, such as a display, when the device is not in use. Factors for determining when a device or its components will not be needed for a period of time and thus can be powered down are typically based in policies that note the amount of time that a device or one or more of its components (e.g., a hard drive) has not been used. When the time period of non-use has exceeded a threshold idle time, the device or component is powered down. The device may subsequently be woken up by the user through user input (e.g. by hitting the space bar or pressing the power button). The devices may also have a reduced power operating mode which is used whenever the device is not connected to mains electricity, e.g. in which the brightness of the display is reduced. Further solutions have been proposed which incorporate additional hardware (e.g. a sensor) within the computing device, which triggers the wake-up of the computing device upon certain events (e.g. detection of a wireless network).
The embodiments described below are not limited to implementations which solve any or all of the disadvantages of known methods of reducing the power consumption of computing devices.